Synthesis of phenyl-substituted fluoranthenes by a diesel-alder and the use thereof

ABSTRACT

A substituted fluoranthene, a light emitting layer including the substituted fluoranthene, a diode including the substituted fluoranthene, and a visual display unit including the substituted fluoranthene.

The present invention relates to fluoranthene derivatives, a process forpreparing them and the use of fluoranthene derivatives as emittermolecules in organic light-emitting diodes (OLEDs), a light-emittinglayer comprising the fluoranthene derivatives of the invention asemitter molecules, an OLED comprising the light-emitting layer of theinvention and devices comprising the OLED of the invention.

Organic light-emitting diodes (OLEDs) exploit the ability of particularmaterials to emit light when they are excited by an electric current.OLEDs are of particular interest as alternatives to cathode ray tubesand liquid crystal displays for producing flat VDUs.

Numerous materials which emit light on excitation by an electric currenthave been proposed.

An overview of organic light-emitting diodes is disclosed, for example,in M. T. Bernius et al., Adv. Mat. 2000, 12, 1737. The compounds usedhave to meet demanding requirements and the known materials are usuallynot able to meet all the demands made.

U.S. Pat. No. 5,281,489 discloses OLEDs which can comprise, inter alia,3,4-benzofluoranthene or monomeric unsubstituted fluoranthene asfluorescent materials. However, monomeric unsubstituted fluoranthene canmigrate under the conditions prevailing in OLEDs during use. The layerof monomeric unsubstituted fluoranthene is not stable, resulting in ashort life of the diodes.

The use of specific fluoranthene derivatives is disclosed in US2002/0022151 A1 and EP-A 1 138 745.

EP-A 1 138 745 relates to an OLED which emits reddish light. This OLEDcomprises an organic layer comprising a compound having a fluorantheneskeleton, with the fluoranthene skeleton being substituted by at leastone amino group and an alkenyl group. According to the description,preference is given to fluoranthene derivatives which have at least 5,preferably at least 6, fused rings. These compounds emit light of alonger wavelength, so that yellow to reddish light can be emitted. Thefluoranthene derivatives disclosed in EP-A 1 138 745 preferably bear anamino group to increase the life of the fluoranthene derivatives.

US 2002/0022151 A1 likewise relates to OLEDs which comprise specificfluoranthene compounds as light-emitting material. These fluoranthenecompounds have at least one diarylamino group.

JP-A 10-169992 relates to benzofluoranthene derivatives and their usein, inter alia, organic light-emitting diodes. The benzofluoranthenederivatives of JP-A 10-169992 display an absorption maximum at about 410nm, i.e. in the blue-violet region.

It is an object of the present invention to provide compounds which aresuitable as emitter molecules in OLEDs, have a long life, are highlyefficient in OLEDs, have an emission maximum in the blue region anddisplay a high quantum yield.

This object is achieved by fluoranthene derivatives of the generalformula I

where the symbols have the following meanings:

-   R¹, R², R³, R⁴, R⁵ are each hydrogen, alkyl, an aromatic radical, a    fused aromatic ring system, a heteroaromatic radical or —CH═CH₂,    (E)- or (Z)—CH═CH—C₆H₅, acryloyl, methacryloyl, methylstyryl,    —O—CH═CH₂ or glycidyl;-   where at least one of the radicals R¹, R² and/or R³ is not hydrogen;-   X is alkyl, an aromatic radical, a fused aromatic ring system, a    heteroaromatic radical or a radical of the formula (I′)

-   -   or an oligophenyl group;

-   n is from 1 to 10 or, in the case of X=oligophenyl group, 1-20;

-   with the proviso that R¹, R², R³ and X are not at the same time    phenyl when R⁴ and R⁵ are hydrogen.

The fluoranthene derivatives of the invention bear substituents whichare linked to the fluoranthene skeleton via a C—C single bond.Surprisingly, the fluoranthene derivatives of the invention aresufficiently stable for them to be used in a light-emitting layer inOLEDs having a long life. Furthermore, the compounds of the inventionhave a very high stability toward photooxidation when used in OLEDs.

It has surprisingly been found that the fluoranthene derivatives of theinvention emit light in the blue region of the visible electromagneticspectrum. This means that the fluoranthene derivatives of the inventiongenerally emit light in the region of the visible electromagneticspectrum from 430 to 480 nm, preferably from 440 to 470 nm, particularlypreferably from 450 to 470 nm.

To produce displays which encompass the colors of the entire visiblespectrum, it is necessary to provide OLEDs which emit light in the redregion of the visible electromagnetic spectrum, OLEDs which emit lightin the green region of the visible electromagnetic spectrum and OLEDswhich emit light in the blue region of the visible electromagneticspectrum. It has been found that the provision of efficient OLEDs whichemit light in the blue region of the visible electromagnetic spectrum isparticularly problematical.

The fluoranthene derivatives of the invention are suitable for producingOLEDs which emit light in the blue region of the visible electromagneticspectrum.

For the purposes of the present patent application, the term “alkyl”refers to a linear, branched or cyclic, substituted or unsubstitutedC₁-C₂₀—, preferably C₁-C₉-alkyl group. If X and R² are an alkyl group,this is preferably a linear or branched C₃-C₁₀—, particularly preferablyC₅-C₉-alkyl group. The alkyl groups can be unsubstituted or besubstituted by aromatic radicals, halogen, nitro, ether or carboxylgroups. The alkyl groups are particularly preferably unsubstituted orsubstituted by aromatic radicals. Preferred aromatic radicals arespecified below. Furthermore, one or more nonadjacent carbon atoms ofthe alkyl group which is/are not bound directly to the fluorantheneskeleton can be replaced by Si, P, O or S, preferably by O or S.

For the purposes of the present patent application, the term “aromaticradical” preferably refers to a C₆-aryl group (phenyl group). This arylgroup can be unsubstituted or be substituted by linear, branched orcyclic C₁-C₂₀—, preferably C₁-C₉-alkyl groups which may in turn besubstituted by halogen, nitro, ether or carboxyl groups or by one ormore groups of the formula I′. Furthermore, one or more carbon atoms ofthe alkyl group can be replaced by Si; P, O, S or N, preferably O or S.Furthermore, the aryl groups or the heteroaryl groups can be substitutedby halogen, nitro, carboxyl groups, amino groups or alkoxy groups orC₆-C₁₄—, preferably C₆-C₁₀-aryl groups, in particular phenyl or naphthylgroups. The term “aromatic radical” particularly preferably refers to aC₆-aryl group which may be substituted by one or more groups of theformula I′, by halogen, preferably Br, Cl or F, amino groups, preferablyNAr′Ar″, where Ar′ and Ar″ are, independently of one another, C₆-arylgroups which, as defined above, can be unsubstituted or substituted andthe aryl groups Ar′ and Ar″ may be substituted by, apart from theabovementioned groups, in each case at least one radical of the formulaI; and/or nitro groups. This aryl group is very particularly preferablyunsubstituted or substituted by NAr′Ar″.

For the purposes of the present patent application, the term “fusedaromatic ring system” refers to a fused aromatic ring system whichgenerally has from 10 to 20 carbon atoms, preferably from 10 to 14carbon atoms. These fused aromatic ring systems can be unsubstituted orbe substituted by linear, branched or cyclic C₁-C₂₀—, preferablyC₁-C₉-alkyl groups which may in turn be substituted by halogen, nitro,ether or carboxyl groups. Furthermore, one or more carbon atoms of thealkyl group can be replaced by Si, P, O, S or N, preferably O or S.Furthermore, the fused aromatic groups can be substituted by halogen,nitro, carboxyl groups, amino groups or alkoxy groups or C₆-C₁₄—,preferably C₆— to C₁₀-aryl groups, in particular phenyl or naphthylgroups. The term “fused aromatic ring system” preferably refers to afused aromatic ring system which may be substituted by halogen,preferably Br, Cl or F, amino groups, preferably NAr′Ar″, where Ar andAr′ are, independently of one another, C₆-aryl groups which, as definedabove, may be unsubstituted or substituted and the aryl groups Ar′ andAr″ may be substituted by, apart from the abovementioned groups, in eachcase at least one radical of the formula I′, or nitro groups. Veryparticular preference is given to the fused aromatic ring system beingunsubstituted. Suitable fused aromatic ring systems are, for example,naphthalene, anthracene, pyrene, phenanthrene or perylene.

For the purposes of the present patent application, the term“heteroaromatic radical” refers to a C₄-C₁₄—, preferably C₄-C₁₀—,particularly preferably C₄-C₅-heteroaryl group containing at least one Nor S atom. This heteroaryl group can be unsubstituted or be substitutedby linear, branched or cyclic C₁-C₂₀—, preferably C₁-C₉-alkyl groupswhich may in turn be substituted by halogen, nitro, ether or carboxylgroups. Furthermore, one or more carbon atoms of the alkyl group can bereplaced by Si, P, O, S or N, preferably O or S. Furthermore, theheteroaryl groups can be substituted by halogen, nitro, carboxyl groups,amino groups or alkoxy groups or C₆-C₁₄—, preferably C₆-C₁₀-aryl groups.The term “heteroaromatic radical” particularly preferably refers to aheteroaryl group which may be substituted by halogen, preferably Br, Clor F, amino groups, preferably NArAr′, where Ar and Ar′ are,independently of one another, C₆-aryl groups which, as defined above,may be unsubstituted or substituted, or nitro groups. Very particularpreference is given to the heteroaryl group being unsubstituted.

For the purposes of the present patent application, the term“oligophenyl” refers to a group of the general formula (IV)

where Ph is in each case phenyl which may in turn be substituted in all5 substitutable positions by a group of the formula (IV);

-   m¹, m², m³-   m⁴ and m⁵ are each, independently of one another, 0 or 1, where at    least one index m¹, m², m³, m⁴ or m⁵ is at least 1.

Preference is given to oligophenyls in which m¹, m³ and m⁵ are each 0and m² and m⁴ are each 1 or oligophenyls in which m¹, m², m⁴ and m⁵ areeach 0 and m³ is 1, and also oligophenyls in which m² and m⁴ are each 0and m¹, m⁵ and m³ are each 1.

The oligophenyl group can thus be a dendritic, i.e. hyperbranched,group, in particular when m¹, m³ and m⁵ are each 0 and m² and m⁴ areeach 1 or when m² and m⁴ are each 0 and m¹, m³ and m⁵ are each 1 and thephenyl groups are in turn substituted in from 1 to 5 of theirsubstitutable positions by a group of the formula (IV), preferably in 2or 3 positions, particularly preferably, in the case of substitution in2 positions, in each case in the meta position relative to the point oflinkage to the base structure of the formula (IV) and, in the case ofsubstitution in 3 positions, in each case in the ortho position and inthe para position relative to the point of linkage to the base structureof the formula (TV).

However, the oligophenyl group can also be essentially unbranched,particularly when only one of the indices m¹, m², m³, m⁴ and m⁵ is 1,with preference being given to m³ being 1 and m¹, m², m⁴ and m⁵ being 0in the unbranched case. The phenyl group can in turn be substituted infrom 1 to 5 of its substitutable positions by a group of the formula(IV); the phenyl group is preferably substituted in one of itssubstitutable positions by a group of the formula (IV), particularlypreferably in the para position relative to the point of linkage to thebase structure. Hereinafter, the substituents linked directly to thebase structure will be referred to as first substituent generations. Thegroup of the formula (IV) can in turn be substituted as defined above.Hereinafter, the substituents linked to the first substituent generationwill be referred to as second substituent generation.

Any desired number of further substituent generations analogous to thefirst and second substituent generations are possible. Preference isgiven to oligophenyl groups having the abovementioned substitutionpatterns and having a first substituent generation and a secondsubstituent generation or oligophenyl groups which have only a firstsubstituent generation.

For the purposes of the present patent application, the term“oligophenyl group” also refers to groups which are based on a basestructure of one of the formulae V, VI and VII:

where Q is in each case a bond to a radical of the formula I′ or a groupof the formula VIII:

where Ph is in each case phenyl which may in turn be substituted by agroup of the formula VIII in a maximum of four positions correspondingto the substitution pattern of the central phenyl ring of the group ofthe formula VIII;

-   n¹, n², n³ and n⁴ are each, independently of one another, 0 or 1,    with n¹, n², n³ and n⁴ preferably being 1.

The oligophenyl groups of the formulae V, VI and VII can thus bedendritic, i.e. hyperbranched, groups.

The oligophenyls of the formulae IV, V, VI and VII are substituted byfrom 1 to 20, preferably from 4 to 16, particularly preferably from 4 to8, radicals of the formula (I′), where one phenyl radical can besubstituted by one, no or a plurality of radicals of the formula (I′). Aphenyl radical is preferably substituted by one or no radical of theformula (I′), with at least one phenyl radical being substituted by aradical of the formula (I′).

Very particularly preferred compounds of the formula I in which X is anoligophenyl radical of the general formula IV are shown below:

Very particularly preferred compounds of the formula I in which X is anoligophenyl radical of the general formula V, VI or VII are shown below:

The radicals R¹, R², R³, R⁴, R⁵ and X can be selected independently fromamong the abovementioned radicals, with the proviso that at least one ofthe radicals R¹, R² and/or R³ is not hydrogen and R¹, R², R³ and X arenot at the same time phenyl when R⁴ and R⁵ are hydrogen.

R⁴ and R⁵ are preferably hydrogen.

R¹ and R³ are each preferably an aromatic radical, a fused aromatic ringsystem or a radical of the formula I′, particularly preferably anaromatic radical, with preferred embodiments of the aromatic radicalhaving been described above. Very particular preference is given to R¹and R³ being phenyl.

R² is preferably hydrogen, alkyl, with preferred embodiments of thealkyl radical having been mentioned above, particularly preferablyC₁-C₉-alkyl which is very particularly preferably unsubstituted andlinear, an aromatic radical, with preferred aromatic radicals havingbeen mentioned above, particularly preferably a phenyl radical.

X is preferably an aromatic radical, with preferred aromatic radicalshaving been mentioned above, particularly preferably a C₆-aryl radicalwhich, depending on n, is substituted by from one to three fluoranthenylradicals, or a fused aromatic ring system, with preferred fused aromaticring systems having been mentioned above, particularly preferably aC₁₀-C₁₄ fused aromatic ring system, very particularly preferablynaphthyl or anthracenyl, with the fused aromatic ring system beingsubstituted, depending on n, by from one to three fluoranthenylradicals. If X is an aromatic radical having 6 carbon atoms, it ispreferably substituted by fluoranthenyl radicals in the 1 and 4positions or in the 1, 3 and 5 positions. If X is, for example, ananthracenyl radical, this is preferably substituted by fluoranthenylradicals in the 9 and 10 positions. For the present purposes,fluoranthenyl radicals are groups of the formula I′

It is also possible for the radical X itself to be a fluoranthenylradical of the formula I′.

Furthermore, X can be an oligophenyl group, with preferred oligophenylgroups having been mentioned above. Preference is given to anoligophenyl group of the general formula (IV), where m¹, m², m³, m⁴ andm⁵ are each 0 or 1, with at least one of the indices m¹, m², m³, m⁴ andm⁵ being 1.

n is an integer from 1 to 10, preferably from 1 to 4, particularlypreferably from 1 to 3, very particularly preferably 2 to 3. This meansthat the fluoranthene derivatives of the general formula I preferablyhave more than one fluoranthenyl radical of the general formula I′.Preference is thus likewise given to compounds in which X itself is afluoranthenyl radical. If X is an oligophenyl group, n is an integerfrom 1 to 20, preferably from 4 to 16.

Very particular preference is given to fluoranthene derivatives of thegeneral formula I which contain no heteroatoms.

In a very particularly preferred embodiment, X is an optionallysubstituted phenyl radical and n is 2 or 3. This means that the phenylradical is substituted by 2 or 3 radicals of the formula I′. The phenylradical preferably contains no further substituents. When n is 2, theradicals of the formula I′ are in the para positions relative to oneanother. If n is 3, the radicals are in the meta positions relative toone another.

In a further preferred embodiment, X is an optionally substituted phenylradical and n is 1, i.e. the phenyl radical is substituted by oneradical of the formula I′.

Preference is also given to X being an anthracenyl radical and n being2. This means that the anthracenyl radical is substituted by tworadicals of the formula I′. These radicals are preferably located in the9 and 10 positions of the anthracenyl radical.

The preparation of the novel fluoranthene derivatives of the generalformula I can be carried out by all suitable methods known to thoseskilled in the art. In a preferred embodiment, the fluoranthenederivatives of the formula I are prepared by reaction ofcyclopentaacenaphthenone derivatives (hereinafter referred to asacecyclone derivatives). Suitable methods of preparing compounds of theformula I in which n is 1 are disclosed, for example, in Dilthey et al.,Chem. Ber. 1938, 71, 974, and Van Allen et al., J. Am. Chem. Soc., 1940,62, 656.

In a preferred embodiment, the novel fluoranthene derivatives of thegeneral formula I are prepared by reacting acecyclone derivatives withalkynyl compounds.

The present invention therefore further provides a process for preparingthe fluoranthene derivatives of the invention by reaction of a compoundof the formula (II)

with an alkynyl compound of the formula (III)X—(≡R²)_(n)   (III)and subsequent elimination of carbon monoxide,

-   where the symbols have the following meanings:-   R¹, R², R³, R⁴, R⁵ are each hydrogen, alkyl, an aromatic radical, a    fused aromatic ring system, a heteroaromatic radical or —CH═CH₂,    (E)- or (Z)—CH═CH—C₆H₅, acryloyl, methacryloyl, methylstyryl,    —O—CH═CH₂ or glycidyl;-   where at least one of the radicals R¹, R² and/or R³ is not hydrogen;-   X is alkyl, an aromatic radical, a fused aromatic ring system, a    heteroaromatic radical or a radical of the formula (I′)

-   -   or an oligophenyl group; and

-   n is from 1 to 10 or, in the case of X=oligophenyl group, from 1 to    20.

The acecyclone derivative of the formula II is prepared by methods knownfrom the prior art, for example by a method in Dilthey et al., J. prakt.Chem. 1935, 143, 189, in which the synthesis of acecyclone(7,9-diphenyl-cyclopenta[a]acenaphthylen-8-one). Derivatives ofacecyclone can be obtained in an analogous manner.

The alkynyl compounds of the formula III can likewise be prepared bymethods known to those skilled in the art. Suitable methods aredisclosed, for example, in Hagihara et al., Synthesis (1980), 627, andL. Cassar, J. Organomet. Chem. 93 (1979), 253.

The ratio of the acecyclone derivative of the formula II to the alkynylcompound of the formula III is dependent on the number of fluoranthenylradicals which the desired fluoranthene derivative of the formula I isto bear, i.e. the ratio of acecyclone derivative of the formula II tothe alkynyl compound of the formula III is dependent on n. In general,the acecyclone derivative (II) and the alkynyl compound (III) are usedin a molar ratio of from n:1 to n+15%:1, preferably from n:1 to n+10%:1.When n=1, an approximately equimolar ratio is preferred, and when n>1, aratio of acecyclone derivative (II) to alkynyl compound (III) of n+10%:1 is preferably employed. Suitable values of n have been mentionedabove.

In a reaction of acecyclone derivatives of the formula II with analkynyl compound of the formula III in which n is 1, the reaction iscarried out using a molar ratio of the acecyclone derivative of theformula II to the alkynyl compound of the formula III of generally from1:1 to 1.3:1, preferably from 1:1 to 1.1:1.

In a reaction of the acecyclone derivative of the formula II with analkynyl compound of the formula III in which n is 2, the reaction iscarried out using a molar ratio of the acecyclone compound of theformula II to the alkynyl compound of the formula II of generally from2:1 to 2.5:1, preferably from 2.1:1 to 2.3:1.

If the acecyclone compound of the formula II is reacted with an alkynylcompound of the formula III in which n is 3, the reaction is carried outusing a molar ratio of the acecyclone compound of the formula II to thealkynyl compound of the formula III of generally from 3:1 to 3.5:1,preferably from 3.2:1 to 3.4:1.

Preferred radicals R¹, R³, R⁴ and R⁵ of the acecyclone derivative of theformula II and preferred radicals X and R² of the alkynyl compound ofthe formula III and preferred indices n of the alkynyl compound of theformula III correspond to the preferred radicals R¹, R², R³, R⁴, R⁵ andX and the preferred indices n which have been mentioned in respect ofthe novel fluoranthene derivatives of the general formula I.

In a very particularly preferred embodiment, R⁴ and R⁵ are each hydrogenand R¹ and R³ are each phenyl. Thus, the acecyclone derivative of theformula II which is used is very particularly preferably acecycloneitself.

Very particularly preferred alkynyl compounds are, for example, those inwhich n is 1, e.g. 9-nonadecyne, 1-octyne, 1-decyne and 1-octadecyne,those in which n is 2, e.g. 1,4-diethynylbenzene and9,10-bisphenylethynylanthracene and also 2,4-hexadiyne, and those inwhich n is 3, e.g. 1,3,5-triethynylbenzene.

If X is an oligophenyl, the alkynyl compounds used are oligophenylderivatives which bear precisely n free acetylene groups (—C≡C—H).

The reaction in the process of the invention is a Diels-Alder reactionwith subsequent elimination of carbon monoxide.

The reaction is generally carried out in a solvent, preferably in anorganic nonpolar solvent, particularly preferably in an organic nonpolarsolvent having a boiling point which is generally above 100° C.,preferably above 140° C., particularly preferably above 260° C.

Suitable solvents are, for example, toluene, xylene, diphenyl ether,methylnaphthalene, mesitylene, glycols and their ethers, decalin andmixtures of the solvents mentioned.

In a preferred embodiment of the process of the invention, theacecyclone derivative of the formula II and the alkynyl compound of theformula III are introduced together into the organic solvent and heatedto temperatures of generally from 140 to 260° C., preferably from 140 to170° C. or from 240 to 260° C. The temperature is dependent on thereactivity of the starting materials. Terminal alkynes (R²═H in theformula (II)) generally react at relatively low temperatures, preferablyfrom 140 to 190° C., particularly preferably from 140 to 170° C., veryparticularly preferably from 140 to 160° C., while internal alkynes(R²≠H in the formula (III)) generally react at higher temperatures,preferably from 190 to 260° C., preferably from 220 to 260° C.,particularly preferably from 240 to 260° C. The reaction time isgenerally from 8 to 30 hours. The reaction time depends on the bulkinessof R² and on n in the formula III. The reaction time in the case of n=1is preferably from 8 to 18 hours, particularly preferably from 10 to 16hours, very particularly preferably from 14 to 16 hours. When n=2, thereaction time is preferably from 18 to 28 hours, particularly preferablyfrom 20 to 26 hours, very particularly preferably from 22 to 26 hours.When n=3, the reaction time is preferably from 24 to 30 hours,particularly preferably from 26 to 30 hours, very particularlypreferably from 28 to 30 hours.

The reaction mixture obtained is precipitated in a polar solvent, forexample in methanol or ethanol, or, if appropriate, in nonpolar solventssuch as cyclohexane. In the case of particularly soluble fluoranthenederivatives, the precipitation step can be omitted. The product obtainedis then worked up by methods known to those skilled in the art. Thework-up is preferably carried out by column chromatography, particularlypreferably on silica gel. As eluant, it is possible to use any suitableeluant or eluant mixture. Very particular preference is given to usingan ethyl acetate/cyclohexane mixture.

The novel fluoranthene derivatives of the general formula I which areobtained have an absorption maximum in the ultraviolet region of theelectromagnetic spectrum and an emission maximum in the blue region ofthe electromagnetic spectrum. The quantum yield of the fluoranthenederivatives of the invention is generally from 20 to 75% in toluene. Ithas been found that fluoranthene derivatives of the general formula I inwhich n is 2 or 3 display particularly high quantum yields of above 50%.

The fluoranthene derivatives of the invention are suitable for emittingelectromagnetic radiation in the blue region of the visibleelectromagnetic spectrum when used in organic light-emitting diodes(OLEDs).

The present invention therefore also provides for the use offluoranthene derivatives of the general formula (I)

where the symbols have the following meanings:

-   R¹, R², R³, R⁴, R⁵ are each hydrogen, alkyl, an aromatic radical, a    fused aromatic ring system, a heteroaromatic radical or —CH═CH₂,    (E)- or (Z)—CH═CH—C₆H₅, acryloyl, methacryloyl, methylstyryl,    —O—CH═CH₂ or glycidyl;-   where at least one of the radicals R¹, R² and/or R³ is not hydrogen;-   X is alkyl, an aromatic radical, a fused aromatic ring system, a    heteroaromatic radical or a radical of the formula (I′)

-   -   or an oligophenyl group;

-   n is from 1 to 10 or, in the case of X=oligophenyl group, from 1 to    20;    as emitter molecule in organic light-emitting diodes (OLEDs).    Preferred fluoranthene derivatives and processes for preparing them    have been mentioned above.

Organic light-emitting diodes are basically made up of a plurality oflayers. Various layer sequences are possible, e.g.:

-   -   anode/hole transport layer/light-emitting layer/cathode;    -   anode/light-emitting layer/electron transport layer/cathode;    -   anode/hole transport layer/light-emitting layer/electron        transport layer/cathode.

The novel fluoranthene derivatives of the general formula I arepreferably used as emitter molecules in the light-emitting layer. Thepresent invention therefore also provides a light-emitting layercomprising one or more fluoranthene derivatives of the general formula I

where the symbols have the following meanings:

-   R¹, R², R³, R⁴, R⁵ are each hydrogen, alkyl, an aromatic radical, a    fused aromatic ring system, a heteroaromatic radical or —CH═CH₂,    (E)- or (Z)—CH═CH—C₆H₅, acryloyl, methacryloyl, methylstyryl,    —O—CH═CH₂ or glycidyl;-   where at least one of the radicals R¹, R² and/or R³ is not hydrogen;-   X is alkyl, an aromatic radical, a fused aromatic ring system, a    heteroaromatic radical or a radical of the formula (I′)

-   -   or an oligophenyl group;

-   n is from 1 to 10 or, in the case of X=oligophenyl group, from 1 to    20;    as emitter molecule. Preferred fluoranthene derivatives and    processes for preparing them have been mentioned above.

The fluoranthene derivatives of the invention can be used in any of theabovementioned layers selected from among the light-emitting layer, theelectron transport layer and the hole transport layer. The fluoranthenederivatives of the invention are preferably used as emitters in thelight-emitting layer. In the light-emitting layer, the fluoranthenederivatives are preferably used as such, i.e. without addition offurther substances. However, it is also possible to use customarylight-emitting materials, dopants, hole-transporting substances and/orelectron-transporting substances in addition to the fluoranthenederivatives of the invention. If the fluoranthene derivatives of theinvention are not used as such, they can be introduced into any of theabovementioned layers in a concentration of from 1 to 70% by weight,preferably from 1 to 20% by weight.

The individual abovementioned layers of the OLEDs can in turn be made upof two or more layers. For example, the hole transport layer can be madeup of a layer into which holes are injected from the electrode,hereinafter referred to as hole injection layer, and a layer whichtransports holes away from the hole injection layer to thelight-emitting layer. This layer will hereinafter be referred to as holetransport layer. The electron transport layer can likewise consist of aplurality of layers, e.g. a layer into which electrons are injected bythe electrode, hereinafter referred to as electron injection layer, anda layer which receives electrons from the electron injection layer andtransports them into the light-emitting layer, hereinafter referred toas electron transport layer. Each of these layers is selected accordingto factors such as energy level, heat resistance and charge carriermobility, and also energy difference between the layers mentioned andthe organic layers or the metal electrodes.

Suitable materials which can be used as base material in combinationwith the novel fluoranthene derivatives of the general formula I in thelight-emitting layer are anthracene, naphthalene, phenanthrene, pyrene,tetracene, corenene, chrysene, fluorescein, perylene, phthaloperylene,naphthaloperylene, perynone, phthaloperynone, naphthaloperynone,diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, aldazine,bisbenzooxazoline, bisstyryl, pyrazine, cyclopentadiene, metal complexesof quinoline, metal complexes of aminoquinoline, metal complexes ofbenzoquinoline, imine, diphenylethylene, vinylanthracene,diaminocarbazole, pyran, thiopyran, polymethine, merocyanine, chelatesof oxinoid compounds with imidazoles, quinacridone, rubrene, stilbenederivatives and fluorescent pigments.

As hole-transporting material, use is generally made of a compound whichis capable of taking up the holes from the anode and transporting holesand at the same time is suitable for injecting the holes into thelight-emitting layer. Suitable hole-transporting materials are, forexample, metal complexes of phthalocyanine, of naphthalocyanine, ofporphyrin, pyrazolones, tetrahydroimidazoles, hydrazones,acylhydrazones, polyarylalkanes, thiophenes, tertiary aromatic aminessuch as triphenylamines of the benzidine type, triphenylamines of thestyrylamine type, triphenylamines of the diamine type, derivatives ofthese compounds, silanamines, in particular silanamines bearingtriphenylsilyl groups, and macromolecular compounds such aspolyvinylcarbazoles, polyvinylsilanes, polythiophene, poly(p-phenylene)and conductive macromolecules. Particularly preferred hole-transportingmaterials are disclosed, for example, in EP-A 1 138 745 and Chen et al.Macromol. Symp. 125, 9 to 15 (1997).

Suitable electron-transporting materials are compounds which are capableof transporting electrons and can themselves inject electrons into thelight-emitting layer. Suitable electron-transporting materials are, forexample, oxazoles, oxadiazoles, triazoles, imidazoles, imidazolones,imidazolethiones, fluoranone, anthraquinone dimethane, diphenoquinone,thiopyran dioxide, perylenetetracarboxylic acid, fluorenylidenemethane,distyrylarylenes, arylenes, coumarins and derivatives of the compoundsmentioned and also metal chelates. Particularly useful compounds areAlQ₃ (tris(8-hydroxyquinolato)aluminum), BeBq₂, 1,3,4-oxidazolderivatives (OXDs) such as PBD and 1,2,4-triazoles (TAZs). Furthersuitable compounds are bis(benzimidazolyl) derivatives ofperylenedicarboximide (PD), naphthalenedicarboximide (ND) and thiopyransulfones (TPS). Preferred electron-transporting materials are disclosed,for example, in EP-A 1 138 745.

To increase the stability of the OLEDs of the invention toward heat,moisture and other influences, the OLED can be protected by a protectivelayer on the surface of the OLED, with this protective layer being madeup of, for example, a resin or silicone oil.

As conductive material which is suitable for the anode of the OLED ofthe invention, preference is given to using a material which has a workfunction of ≧4 eV. Suitable materials for the anode are, for example,carbon, vanadium, iron, cobalt, nickel, tungsten, gold, platinum,palladium and alloys of these materials, metal oxides as are used forITO substrates (ITO=indium-tin oxide) and NESA substrates, e.g. tinoxides and indium oxides, and organic conductive polymers such aspolythiophene and polypyrrole.

Suitable conductive materials for the cathode are materials which have awork function of <4 eV. Materials suitable for the cathode are, forexample, magnesium, calcium, tin, lead, titanium, yttrium, lithium,ruthenium, manganese, aluminum and alloys of these materials.

The anode and the cathode can, if appropriate, have a multilayerstructure consisting of two or more layers.

The OLEDs of the present invention preferably additionally have a layerof a chalcogenide, a metal halide or a metal oxide on the surface of atleast one electrode pair. Particular preference is given to applying alayer of a chalcogenide (including an oxide) of a metal, e.g. silicon oraluminum, to the surface of the anode on the side pointing in thedirection of the light-emitting layer. A layer of a metal halide or ametal oxide is preferably applied to the surface of the cathode whichpoints in the direction of the light-emitting layer. The twoabovementioned layers can improve the stability of the OLED. Preferredmaterials for the layers mentioned are a mention, for example, in EP-A 1138 745.

Further preferred embodiments of the individual layers of the OLEDs arelikewise described in EP-A 1 138 745.

In general, at least one side of the OLED of the invention istransparent in the wavelength range in which light is to be emitted inorder to make efficient light emission possible. The transparentelectrode is generally applied by vapor deposition or sputtering. Theelectrode preferably has a transparency to light of ≧10% on thelight-emitting side of the OLED. Suitable materials are known to thoseskilled in the art. For example, glass substrates or transparent polymerfilms can be used.

The production of the OLEDs of the invention is known to those skilledin the art. It is possible for each layer of the OLED to be produced bya dry process for film formation, e.g. vapor deposition, sputtering,plasma plating or ion plating, or a wet process for film formation, e.g.spin coating, dipping or flow coating. The thickness of the individuallayers is not subject to particular restrictions and customarythicknesses are known to those skilled in the art. Suitable thicknessesof the layers are generally in the range from 5 nm to 10 μm. Preferenceis given to thicknesses of from 10 nm to 0.2 μm. The procedures forcarrying out dry processes or wet processes for film formation are knownto those skilled in the art.

The present invention thus further provides an OLED comprising alight-emitting layer which comprises one or more fluoranthenederivatives of the general formula (I)

where the symbols have the following meanings:

-   R¹, R², R³, R⁴, R⁵ are each hydrogen, alkyl, an aromatic radical, a    fused aromatic ring system, a heteroaromatic radical or —CH═CH₂,    (E)- or (Z)—CH═CH—C₆H₅, acryloyl, methacryloyl, methylstyryl,    —O—CH═CH₂ or glycidyl;-   where at least one of the radicals R¹, R² and/or R³ is not hydrogen;-   X is alkyl, an aromatic radical, a fused aromatic ring system, a    heteroaromatic radical or a radical of the formula (I′)

-   -   or an oligophenyl group;

-   n is from 1 to 10 or, in the case of X=oligophenyl group, from 1 to    20;    as emitter molecules. Preferred compounds of the general formula I    and processes for preparing them have been mentioned above.

The OLED of the invention can be used in numerous devices. The presentinvention thus further provides a device selected from the groupconsisting of stationary VDUs such as VDUs of computers, televisions,VDUs in printers, kitchen appliances and advertising signs, lighting,information signs and mobile VDUs such as VDUs in mobile telephones,laptops, vehicles and also destination displays on buses and trains.

The following examples illustrate the invention.

EXAMPLES 7,8,9,10-Tetraphenylfluoranthene

7,8,9,10-Tetraphenylfluoranthene was synthesized as described by Diltheyet al., Chem. Ber. 1938, 71, 974 and Van Allen et al., J. Am. Chem.Soc., 1940, 62, 656.

λ_(max,em) (Toluene)=462 nm, quantum yield (toluene): 35%; λ_(max, em)(film)=472 nm

8-Naphthyl-2-yl-7,10-diphenylfluoranthene

1.281 g of 1-ethynylnaphthalene and 3 g of7,9-diphenylcyclopenta[a]acenaphthylen-8-one (acecyclone, synthesized asdescribed by Dilthey et al., J. prakt. Chem. 1935, 143, 189) weredissolved in 20 g of xylene and refluxed for 16 hours. Precipitation inmethanol and chromatography on silica gel (Merck silica gel 60, ethylacetate/cyclohexane) gave 3.1 g of a beige solid.

λ_(max, em) (toluene)=468 nm, quantum yield (toluene): 31%, λ_(max,em)(film)=466 nm

8-Nonyl-9-octyl-7,10-diphenylfluoranthene

1.484 g of 9-nonadecyne and 2 g of acecyclone were dissolved in 15 g ofdiphenyl ether and refluxed for 16 hours. Precipitation in methanol andchromatography on silica gel (Merck silica gel 60, ethylacetate/cyclohexane) gave 8-nonyl-9-octyl-7,10-diphenylfluoranthene as abrownish solid.

λ_(max, em) (toluene)=468 nm, quantum yield (toluene): 21%

Benzene-1,4-bis-(2,9-diphenylfluoranth-1-yl)

1 g of 1,4-diethynylbenzene and 6.5 g of acecyclone were dissolved in 22g of xylene and refluxed for 16 hours. Chromatography on silica gel(Merck silica gel 60, ethyl acetate/cyclohexane) gavebenzene-1,4-bis(2,9-diphenylfluoranth-1-yl) as a yellowish solid.

λ_(max, em) (toluene)=461 nm, quantum yield (toluene): 59%; λ_(max, em)(film)=467 nm

Benzene-1,3,5-tris(2,9-diphenylfluoranth-1-yl)

0.2 g of 1,3,5-triethynylbenzene and 2 g of acecyclone were dissolved in20 g of xylene and refluxed for 24 hours. Precipitation in methanol andfiltration through silica gel (Merck silica gel 60, ethylacetate/cyclohexane) gave 0.6 g of a beige solid.

λ_(max, em) (toluene)=459 nm, quantum yield (toluene): 51%; λ_(max, em)(film)=467 nm

9,9′-Dimethyl-7,10,7′,10′′-tetraphenyl-[8,8′]bifluoranthene

0.61 g of 2,4-hexadiyne and 8 g of acecyclone were dissolved in 15 g ofdiphenyl ether and refluxed for 26 hours. Distilling off the solvent andchromatography on silica gel (Merck silica gel 60, ethylacetate/cyclohexane) gave 4.2 g of a beige solid.

λ_(max, em) (toluene)=463 nm, quantum yield (toluene): 34%

9,10-Bis(2,9,10-triphenylfluoranthen-1-yl)anthracene,9,10-bis(9,10-diphenyl-2-octylfluoranthen-1-yl)anthracene

R=phenyl, octyl

Phenyl derivative: 0.92 g of 9,10-bisphenylethynylanthracene and 2 g ofacecyclone were dissolved in 15 g of diphenyl ether and refluxed for 14hours. Distilling off the solvent and precipitation in methanol gave 0.7g of a gray solid.

λ_(max, em) (toluene)=456 nm, quantum yield (toluene): 72%, λ_(max, em)(film)=461 nm

Alkyl derivative: 0.91 g of 9,10-bis(4-octylphenylethynyl)anthracene(synthesized by double Pd(0)-catalyzed Hagihara-Sonogashira coupling of1-decyne with 9,10-dibromoanthracene (as described by Hagihara et al.,Synthesis 1980, 627) and 2.1 g of acecyclone were dissolved in 15 g ofdiphenyl ether and refluxed for 10 hours. Distilling off the solvent,precipitation in ethanol and chromatography on silica gel (Merck silicagel 60, ethyl acetate/cyclohexane) gave9,10-bis(9,10-diphenyl-2-octylfluoranthen-1-yl)anthracene (1.8 g).

λ_(max, em) (toluene)=455 nm, quantum yield (toluene): 44%

1. A fluoranthene of the general formula I

wherein R¹, R², R³ are each independently hydrogen, alkyl, an aromaticradical, a fused aromatic ring system, or a heteroaromatic radical;wherein at least one of the radicals R¹, R² and/or R³ is not hydrogen;wherein X is an alkyl radical or a radical of the formula (I′)

or an oligophenyl group; and wherein, when X is a radical of the formula(I′), in the radial of the formula (I′), R¹ to R³ have the same meaningsas in formula (I); wherein the oligophenyl group is a group of thegeneral formula (IV)

wherein Ph is in each case phenyl which, optionally, may be substitutedin all 5 substitutable positions by a group of the formula (IV),wherein, in the oligophenyl group of the general formula (IV), theindexes m¹, m³ and m⁵ are each 0 and m² and m⁴ are each 1, or theindexes m² and m⁴ are each 0 and m¹, m³ and m⁵ are each 1; when X is analkyl radical n is 2 or 3, when X is a radical of the formula (I′) n is1, when X is an oligophenyl group n is 1; with the proviso that R¹, R²,R³ and X are not at the same time phenyl.
 2. The fluoranthene accordingto claim 1, wherein R¹ and R³ are each a phenyl radical.
 3. Afluoranthene of the general formula I

wherein R¹, R², R³ are each independently hydrogen, alkyl, an aromaticradical, a fused aromatic ring system, or a heteroaromatic radical;wherein at least one of the radicals R¹, R² and/or R³ is not hydrogen;wherein X is an alkyl radical, and n is 2 or
 3. 4. An organiclight-emitting diode comprising as an emitter molecule a fluoranthene ofthe general formula (I)

wherein R¹, R², R³ are each independently hydrogen, alkyl, an aromaticradical, a fused aromatic ring system, or a heteroaromatic radical;wherein at least one of the radicals R¹, R² and/or R³ is not hydrogen;wherein X is an alkyl radical or a radical of the formula (I′)

or an oligophenyl group; wherein, when X is a radical of the formula(I′), in the radial of the formula (I′), R¹ to R³ have the same meaningsas in formula (I); wherein the oligophenyl group is a group of thegeneral formula (IV)

wherein Ph is in each case phenyl which, optionally, may be substitutedin all 5 substitutable positions by a group of the formula (IV),wherein, in the oligophenyl group of the general formula (IV), theindexes m¹, m³ and m⁵ are each 0 and m² and m⁴ are each 1, or theindexes m² and m⁴ are each 0 and m¹, m³ and m⁵ are each 1; and when X isan alkyl radical n is 2 or 3, when X is a radical of the formula (I′) nis 1, when X is an oligophenyl group n is
 1. 5. A light-emitting layercomprising one or more floranthenes of the general formula (I) accordingto claim
 1. 6. An organic light-emitting diode (OLED) comprising thelight-emitting layer according to claim
 5. 7. A device selected from thegroup consisting of a stationary VDU and a mobile VDU; comprising anOLED according to claim
 6. 8. An organic light-emitting diode comprisingas an emitter molecule the fluoranthene according to claim
 1. 9. Alight-emitting layer comprising one or more fluoranthenes of the generalformula (I) as defined in claim 2 as emitter molecule(s).
 10. An organiclight-emitting diode (OLED) comprising the light-emitting layeraccording to claim
 9. 11. A device selected from the group consisting ofa stationary VDU and a mobile VDU; comprising the OLED according toclaim
 10. 12. The device according to claim 7, wherein the device is astationary VDU, and wherein the stationary VDU is selected from thegroup consisting of a computer VDU, a television VDU, a printer VDU, akitchen appliance VDU, an advertising sign VDU, a lighting VDU, and aninformation sign VUD.
 13. The device according to claim 7, wherein thedevice is a mobile VDU, and wherein the mobile VDU is selected from thegroup consisting of a mobile telephone VDU, a laptop VDU, a vehicle VDU,a bus destination VDU, and a train destination VDU.
 14. The deviceaccording to claim 11, wherein the device is a stationary VDU, andwherein the stationary VDU is selected from the group consisting of acomputer VDU, a television VDU, a printer VDU, a kitchen appliance VDU,an advertising sign VDU, a lighting VDU, and an information sign VDU.15. The device according to claim 11, wherein the device is a mobileVDU, and wherein the mobile VDU is selected from the group consisting amobile telephone VDU, a laptop VDU, a vehicle VDU, a bus destination VDUand a train destination VDU.
 16. The device of claim 7, wherein thedevice is a stationary VDU.
 17. The device of claim 7, wherein thedevice is a mobile VDU.
 18. The device of claim 11, wherein the deviceis a stationary VDU.